During the Second World War Oldfield joined the British Army. He was commissioned as a second lieutenant in the Intelligence Corps in July 1943. Most of his wartime service was in Egypt at the headquarters of SIME in Cairo. This was primarily a counter-intelligence organisation, the role of which was to detect hostile agents in the region and counter their activities. By the end of the war, Oldfield had been promoted to major. In 1946, he was awarded an MBE.
Intelligence career
After the war, Oldfield joined the Secret Intelligence Service, commonly known as MI6. From 1947 to 1949, he was deputy to Brigadier Douglas Roberts, the head of counter-intelligence, with whom he had served in Egypt during the war. After two postings to Singapore he was appointed a CBE. From 1959, he spent four years as the SIS representative in Washington, D.C. This was a key post, important for the maintenance of good relations between the SIS and the Central Intelligence Agency. On his return, he became director of counter-intelligence and deputy to the Chief of the Secret Intelligence ServiceSir Dick White. Oldfield was passed over for promotion when Sir John Rennie succeeded White in 1968. He eventually became director when Rennie resigned in 1973; he held this post until his retirement in 1978. After retiring from the MI6, Oldfield was a Visiting Fellow at All Souls College, Oxford until 1979. In 1979 the new prime minister, Margaret Thatcher, asked Oldfield to coordinate security and intelligence in Northern Ireland. Shortly afterwards it was discovered that he was using the services of male prostitutes. He was subject to a security review to ensure there had not been blackmail or pressure from Soviet counterintelligence. When nothing was discovered, he was told to curb his behaviour and left in his Northern Ireland post. In a statement on the matter to the House of Commons in 1987, Thatcher said: "he had contributed notably to a number of security and intelligence successes which would not have been achieved had there been a breach of security." Oldfield died in March 1981; he is buried in Over Haddon. Oldfield was reputedly one of the models for John le Carré's fictional characterGeorge Smiley, though Le Carré disputes this. In his memoir The Pigeon Tunnel: Stories from My Life Le Carré describes a lunchtime meeting between Oldfield, himself and Alec Guinness; this was intended to provide the actor with a sense of the manner and appearance of an "old spy in retirement". In October 2012 it was reported by the BBC's current affairs program Panorama in October 2012, that he had been linked to the Elm Guest House child abuse scandal, supposedly involving senior MPs and security personnel, by the Operation Midland investigation, and a Metropolitan Police informant. The investigation ended without charges, and in 2017 Oldfield was cleared of all allegations of child abuse at Elm Guest House and elsewhere. The accuser in the Operation Midland case, Carl Beech, was subsequently convicted of making up the allegations in 2019.